One of the theories behind cavity formation has to do with the pH in a persons mouth being perfect for the bacteria to grow and break down your teeth. However

One of the theories behind cavity formation has to do with the pH in a persons mouth being perfect for the bacteria to grow and break down your teeth. However some people seem to have a pH in their mouths that is not appropriate to bacterial growth and therefore they get less cavities. You probably fall within this group and therefore have a smaller chance of getting cavities.